In a manufacturing process of an electronics product, e.g., a manufacturing process of a semiconductor integrated circuit device, various kinds of processing such as film forming, oxidizing, nitriding, diffusing of donors and acceptors, annealing and the like are repeatedly performed on a substrate (a semiconductor wafer).
Miniaturization and high integration of a semiconductor integrated circuit device are currently being developed. As semiconductor elements are miniaturized, a degree of integration of a semiconductor integrated circuit device is improved. Along with this, it can be also further developed to increase an operation speed of the semiconductor integrated circuit device. A recently-available semiconductor integrated circuit device is being integrated in a height direction to meet the requirement of a higher integration degree. With respect to a semiconductor element per se, improvement and development are made day by day in order to obtain more stable electric properties.
If the integration in the height direction or the improvement and development of the semiconductor elements progress, the time necessary for manufacturing one semiconductor integrated circuit device increases. This is because the number of processing procedures required in the manufacture of one semiconductor integrated circuit device increases. For example, if the integration progresses in the height direction, the number of processing procedures such as the number of film forming procedures or the like increases. In an improved or newly-developed semiconductor element, different conductive layers are stacked or a stress liner film for controlling a stress is formed in order to stabilize electric properties. This may also become one cause of increasing the number of processing procedures such as the number of film forming procedures or the like.
As mentioned above, the miniaturization and high integration of a semiconductor integrated circuit or the progress of the improvement and development of a semiconductor element leads to an increase of the number of processing procedures in a manufacturing process and becomes one cause of prolonging a manufacturing time necessary for one semiconductor integrated circuit device. In order to prevent the prolonging of the manufacturing time, it is important to enhance a throughput in each of the processing steps.
One solution of enhancing a throughput in each of the processing steps is batch-type processing by which a plurality of semiconductor wafers is processed at one time. A substrate processing apparatus for performing the batch-type processing has been introduced in the related art. The conventional substrate processing apparatus is a batch-type vertical substrate processing apparatus.
In the batch-type vertical substrate processing apparatus, however, a processing chamber tends to become taller in a height direction in order to process a plurality of semiconductor wafers at one time. For that reason, it may be difficult to uniformly supply a process gas such as a film forming source gas or the like into the processing chamber, so that it will be difficult to secure the wafer in-plane and wafer inter-plane uniformity of thickness of a thin film to be formed.
Thus, in the conventional batch-type vertical substrate processing apparatus, gas introduction division units for defining a plurality of gas introduction portions in a height direction with respect to the processed surfaces of semiconductor wafers are installed in a gas introduction pipe so that a process gas used in the processing can flow toward the respective gas introduction division units.
In a wafer boat (hereinafter referred to as a substrate holder) for stacking and holding a plurality of semiconductor wafers in a height direction, processing division walls (hereinafter referred to as division plates) for dividing a holding part of the substrate holder into a plurality of processing parts (hereinafter referred to as processing subspaces) are installed along the height direction so that the process gas can be supplied from the gas introduction division units to the respective processing subspaces.
In the related art, an interior of a large processing chamber is divided into a plurality of processing subspaces and a process gas is supplied to the respective processing subspaces, thereby enhancing the wafer in-plane and wafer inter-plane uniformity of thickness of a thin film to be formed.
The substrate holder is rotated during the processing. In order to rotate the substrate holder, the division plates of the substrate holder should not make contact with the gas introduction division walls. Accordingly, a clearance (gap) portion is set between the division plates and the gas introduction division walls. In the related art, the clearance portion is set between side surface portions of the division plates extending in the height direction and side surface portions of the gas introduction division walls extending in the height direction.
However, the substrate holder employed in the batch-type vertical substrate processing apparatus is tall in the height direction. While the substrate holder is fabricated to have extremely accurate perpendicularity in the height direction, a small tolerance is predicted in an “inclination” thereof. For that reason, during the rotation of the substrate holder, the substrate holder makes a “swing movement (precession movement)” within a range of the tolerance. An “amplitude” generated in the substrate holder by the “precession movement” becomes larger as the number of semiconductor wafers held by the substrate holder grows larger and as the substrate holder grows taller.
The substrate holder is mounted on a heat insulating tube or a table such that a “deviation (an eccentricity from a rotation center)” does not exist between a center of the substrate holder and a rotation center of the heat insulating mound or the table. However, a tolerance is involved even in this case. When the substrate holder is rotated, the tolerance associated with the mounting position may generate an “amplitude” in the substrate holder.
Under these circumstances, in the substrate holder having an increased height, there is a case that has to secure a distance of the clearance portion of at least about 10 mm if a safety margin for the reliable avoidance of contact is predicted.
The clearance portion is needed to rotate the substrate holder. However, if the clearance portion becomes larger in size, the sealability between the processing subspaces deteriorates. Thus, a process gas may leak from one processing subspace to another processing subspace, or vice versa. For that reason, there may be a situation that the concentration, the flow rate and the like of a process gas existing in the processing subspaces become difficult to control and further that the wafer in-plane and wafer inter-plane uniformity of thickness of a thin film to be formed gets worse again.